On Fri, 2009-12-18 at 18:09 -0500, Jay Smith wrote:

> I am afraid I am not 100% following what you are saying.  Perhaps I
> miscommunicated.  Or perhaps I am just not filling in assumed knowledge
> well enough.
> 
> I want to use Gimp as an image editor.

Well, you say that you want to process thousands of images. Then GIMP is
the wrong tool for the job.

> b) I would like to find a method to remove color profile parasites on
> thousands of images, via the command line.  You have suggested trying
> "tifftopnm | pnmtotiff" do to this.  I will experiment with that, but I
> have a concern as noted below.
> 
> Based on your most recent recommendation, I looked at
>   http://netpbm.sourceforge.net/doc/tifftopnm.html
> and I am not sure how this helps me, unless you are suggesting to
> ROUNDTRIP using these two programs.

But that is exactly the same thing that happens when you open a TIFF
file in GIMP and save it again. The pixel data is loaded into GIMP and
your file is not any longer a TIFF file then, it is a collection of
pixels, let's call it an image. Then when you save it as TIFF again,
this collection of pixels is encoded as a TIFF file. Pretty much exactly
what tifftopnm | pnmtotiff is doind.

> However, I noted it said [below] that theoretically you can lose
> information in certain cases.  I have no idea if my images would be
> affected by that.
> 
> "The PNM output has the same maxval as the Tiff input, except that if
> the Tiff input is colormapped (which implies a maxval of 65535) the PNM
> output has a maxval of 255. Though this may result in lost information,
> such input images hardly ever actually have more color resolution than a
> maxval of 255 provides and people often cannot deal with PNM files that
> have maxval > 255. By contrast, a non-colormapped Tiff image that
> doesn't need a maxval > 255 doesn't have a maxval > 255, so when
> tifftopnm sees a non-colormapped maxval > 255, it takes it seriously and
> produces a matching output maxval. Another exception is where the TIFF
> maxval is greater than 65535, which is the maximum allowed by the Netpbm
> formats. In that case, tifftopnm uses a maxval of 65535, and you lose
> some information in the conversion."

Since GIMP doesn't support a maxval > 255, you would more likely lose
information if you used GIMP for this.


Sven


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